JPMorgan two days ago reversed course and broke off talks to move its headquarters to the Hudson Yards district on Manhattan’s far west side, which would have greatly accelerated development in that area. The bank would have joined Time Warner Inc., luxury-handbag maker Coach Inc., cosmetics maker L’Oreal SA and the city’s first Neiman Marcus department store, all of which have agreed to take space in the once-gritty industrial zone near the Hudson River.